Very lightweight reactive applique armor

ABSTRACT

A multi-layer lightweight protective armor system for application to an unarmored vehicle includes an energy absorbing layer adapted to be mounted adjacent an exterior vehicle surface, an explosive layer formed from an explosive material and disposed on the energy absorbing layer, and a trigger layer disposed on the explosive layer. The trigger layer is operable to initiate an explosion in the explosive layer when a projectile impacts the trigger layer and the energy absorbing layer is operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60/784,190, entitled “Very Lightweight Reactive Appliqué Armor”, filed on Mar. 20, 2006, and the specification thereof is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Reactive appliqué armor is currently in use on armored combat vehicles, principally main battle tanks. This armor operates on the principle of firing an explosive charge at the proper time and location to defeat an incoming round. The armor is attached to the exterior surface of the vehicle, outside the armored surface, facing the threat. When the incoming round reaches the surface of the armor, the reactive armor triggers an explosive charge, which destroys the incoming round before it can penetrate the basic armor of the vehicle. This type of armor depends on the native armor of the vehicle to protect the vehicle and its crew from the explosive blast of the reactive armor, and to defeat any undestroyed fragments of the incoming round. This type of armor is therefore not applicable to protecting unarmored vehicles. Thus, there is a need for a lightweight armor to protect unarmored vehicles against a wide spectrum of threats, from small arms to shaped-charge jet penetrators.

BRIEF SUMMARY OF THE INVENTION

A multi-layer lightweight protective armor system for application to an unarmored vehicle includes an energy absorbing layer adapted to be mounted adjacent an exterior vehicle surface, an explosive layer formed from an explosive material and disposed on the energy absorbing layer, and a trigger layer disposed on the explosive second layer. The trigger layer is operable to initiate an explosion in the explosive layer when a projectile impacts the trigger layer and the energy absorbing layer is operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.

In one embodiment, the energy absorbing layer includes a plurality of sub-layers. Alternatively, the energy absorbing sub-layers are formed from at least one material selected from the group consisting of RPF, metal, polymer, flexible polymer foam, and high strength polymer fabric material. Alternatively, the layers of the system are formed in the shape of a tile and the system comprises a plurality of the tiles arranged in an array on the exterior vehicle surface. Alternatively, each of the tiles has an aspect ratio of approximately 1.0. Alternatively, the explosive layer is formed from an explosive material. Alternatively, the explosive material comprises material such as PETN, C-2, C-3, and C-4, or any other suitable material.

Alternatively, the trigger layer includes a plurality of sub-layers. Alternatively, the trigger sub-layers are formed from at least one of material selected from the group consisting of a metal and a polymer. Alternatively, the trigger layer initiates an explosion utilizing a percussion plate. Alternatively, the trigger layer initiates an explosion utilizing an electrical initiation system. Alternatively, the system further comprises a detonating device disposed in the explosive layer. Alternatively, the system further comprises a spacer layer disposed between the explosive layer and the trigger layer.

Another embodiment provides a multi-layer lightweight protective armor system for application to an unarmored vehicle that includes an energy absorbing layer adjacent an exterior vehicle surface, an explosive layer disposed on the energy absorbing layer and including a detonator disposed therein, a spacer layer disposed on the explosive layer, a trigger layer disposed on the spacer layer, and a firing set including a detonator disposed in the explosive layer. The trigger layer is operable to send a signal to the firing set when a projectile impacts the trigger layer and the firing set is operable to detonate the detonator to initiate an explosion in the explosive layer. The energy absorbing layer is operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.

In one embodiment, the energy absorbing layer includes a plurality of sub-layers. Alternatively, the energy absorbing sub-layers are formed from at least one material selected from the group consisting of RPF, metal, polymer, flexible polymer foam, and high strength polymer fabric material. Alternatively, the trigger layer includes a plurality of sub-layers. Alternatively, the trigger sub-layers are formed from at least one material selected from the group consisting of a metal and a polymer. Alternatively, the trigger layer sends a signal to the firing set when the projectile completes an electrical circuit between two of the trigger sub-layers.

Another embodiment provides a multi-layer lightweight protective armor system for application to an unarmored vehicle that includes an energy absorbing layer adjacent an exterior vehicle surface; an explosive layer disposed on the energy absorbing layer, the explosive layer including a detonator disposed therein; and a trigger layer disposed on the second layer, the trigger layer including a percussion plate operable to initiate an explosion in the explosive layer when a projectile impacts the trigger layer, the energy absorbing layer operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.

In another embodiment, the energy absorbing layer includes a plurality of sub-layers. These energy absorbing sub-layers may comprise RPF, metal, polymer, flexible polymer foam, high strength polymer fabric material, and/or a combination thereof. The trigger layer may include a plurality of sub-layers. These trigger sub-layers may be formed from a metal and/or a polymer, or other suitable materials. In one embodiment, at least one of the trigger sub-layers is a percussion plate, another of the trigger sub-layers is an anvil layer, and another of the trigger sub-layers is a hammer layer. The surfaces of the anvil layer and the hammer layer in contact with the percussion plate may include complementary contours shaped for efficient compression of the percussion plate.

The very lightweight reactive appliqué armor provides protection to unarmored vehicles by providing an energy-absorbing layer comprising four basic components, arranged as layers. Each of these basic layers is not necessarily monolithic, but may have several sub-layers, depending on the specific combination of vehicle to be protected and perceived threat. There must also be some mounting hardware to mount the layer on the surface of the vehicle. In some embodiments there are also electrical components, including a firing set and the necessary connectors, wiring and power source.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

FIG. 1 is a general configuration of the very lightweight reactive appliqué armor of the present invention;

FIG. 2 is a partial fragmentary view of the very lightweight reactive appliqué armor surface of an installation;

FIG. 3 shows an example of an electrically initiated implementation of the very lightweight reactive appliqué armor; and

FIG. 4 shows an example of a percussion initiated implementation of the very lightweight reactive appliqué armor of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring now to FIG. 1, a preferred embodiment of the invention, very light weight reactive appliqué armor system is indicated generally at 1. System 1 includes an energy absorbing layer 2, explosive layer 4, spacer layer 6, to enable firing at the proper time, discussed in more detail below, and trigger layer 8. Energy absorbing layer 2 is nearest the vehicle surface and trigger layer 8 is nearest the threat. Explosive layer 4 includes a charge that detonates to defeat an incoming round.

The very lightweight reactive appliqué armor system 1 provides protection to unarmored vehicles by providing an energy-absorbing layer comprising four basic components, arranged as layers. Each of these basic layers 2, 4, 6, and 8 is not necessarily monolithic, but may have several sub-layers, depending on the specific combination of vehicle to be protected and the perceived threat. Energy absorbing layer 2 is preferably adapted to be mounted on the exterior surface of the vehicle and, therefore, system 1 preferably includes suitable mounting hardware to mount energy absorbing layer 2 onto the exterior surface of the vehicle. In some embodiments, there are also electrical components, including a firing set and the necessary connectors, wiring and power source.

There are at least two possible techniques for initiating the charge in explosive layer 4. In a non-electric embodiment, a percussion plate, or non-electric (NONEL) initiator is (or other suitable initiator) used and no electric components are needed. Spacer layer 6 is eliminated in this embodiment, as will be appreciated by those skilled in the art. In the non-electric embodiment, trigger layer 8 also functions as the initiator layer, serving to directly initiate an explosion in explosive layer 4 when struck by a high energy, high velocity blow.

Alternatively, an electrical firing system is used and the very lightweight reactive appliqué armor system 1 includes a power source for firing the explosive and appropriate electrical wires, connectors and insulation. In the electrically initiated embodiment, when the threat projectile strikes trigger layer, 8, a signal is transmitted to a firing set through embedded wires. The firing set then sends an electrical firing pulse to a detonator, or “squib,” embedded in explosive layer 4. Spacer layer 6 enables the firing set to deliver the firing pulse before the incoming projectile leading edge reaches explosive layer 4. With either the percussion plate or electrical firing system, when explosive layer 4 fires, energy absorbing layer 2 sacrificially contains the blast in the vehicle direction.

In any embodiment of very lightweight reactive appliqué armor system 1, the particular materials for layers 2, 4, 6, and 8 and dimensions chosen are the determiners of success. The materials for layers 2, 4, 6, and 8 of system 1 may be formed from commercial-off-the-shelf light weight components such as, but not limited to, thin ductile metal such as aluminum or the like, flexible polymer foam, high strength polymer fabric armor material (e.g., DuPont's Kevlar®), rigid polyurethane foam, sheet explosive, such as DuPont C-2, C-3, or C-4 Detasheet®, rigid polymer foam, and polymers. System 1 is preferably mounted to an exterior surface of a vehicle by any suitable removable fastener or fastening systems including, but not limited to, a rigid rack including clips or the like, hook-and-loop fasteners or similar fasteners that allow for easy installation and removal of system 1.

EXAMPLES

Two examples are described herein, but other materials and/or dimensions may be utilized to provide a wide variety of embodiments and implementations, as will be appreciated by those skilled in the art. For each of the two examples described herein, the threat is any projectile fired by current military small arms, for example projectiles up to 0.50 cal (12.7 mm). The vehicle to be protected is any unarmored US military personnel transport vehicle.

Referring now to FIG. 2, in both examples, the very lightweight reactive appliqué armor system 1 is in the form of a substantially square tile 10, preferably, but not limited to, 3″ on a side, grouped in a substantially rectangular array on the surface to be protected. Each tile 10 has the layers 2, 4, 6, and 8 as described above, but energy absorbing layer 2 and trigger layer 8 are fabricated from sub-layers, each with a specific purpose and discussed in more detail below. Viewed from a position normal to the protected surface, from the position of an incoming projectile, FIG. 2 shows an array of tiles 10 mounted on surface 12 of a vehicle in a predetermined pattern. Depending on the surface 12 being protected, the size and placement of the predetermined pattern of tiles 10 will vary, as will be appreciated by those skilled in the art.

In each example, while the shape and size is for 3″ square tiles 10, both the dimensions and shape of the tiles 10 may be varied. In some applications, the tiles 10 are triangular, pentagonal, hexagonal, or other shapes as required to cover a surface in an array without gaps. In any application the tiles 10 preferably each have an aspect ratio of approximately 1.0 for best efficiency, defined herein as the ratio of a length of tile 10 to a width of tile 10. Sizes of tiles 10 may be varied from somewhat less than 3″ square (e.g. as low as 1″) to larger panels (e.g. 12″ or more). However, as the size of the tile 10 is increased, the quantity of explosive in explosive layer 4 increases with the square of the linear dimension of all layers 2, 4, 6, and 8. This increase in explosive, in turn, requires an increase in the thickness of energy absorbing layer 2. The thickness of layer 2 must be increased at a slightly more than linear rate as the charge weight in explosive layer 4 increases.

In an electrically initiated reaction embodiment of very lightweight reactive appliqué armor system, indicated generally at 16, each tile 10 preferably has a cross-section such as that shown in FIG. 3. In this example, the energy absorbing layer 2 comprises four sub-layers, designated 2A, 2B, 2C, and 2D. Trigger layer 8 has three sub-layers, 8G, 8H and 8J. System 16 also includes explosive layer 4E and spacer layer 6F. The simple trigger relies on a completed circuit between layers 8G and 8J by the incoming projectile 14. This is in direct response to the threat, and not a general design feature. Layer 8J of trigger layer 8 is preferably formed from aluminum or other suitable material and provides physical protection from light incidental impact for the tile. Layer 8H is preferably formed from a polymer insulating sheet or other suitable material and layer 8G is preferably formed from aluminum or other suitable material. The explosive layer 4E is preferably formed from PETN, in the form of Detasheet®, although any explosive, suitable for the purposes of this invention, may be utilized, as will be appreciated by those skilled in the art. The principal energy absorbing material is preferably rigid polyurethane foam (RPF) or other appropriate material in layer 2D, where most of the blast energy is dissipated. Layer 2C preferably comprises several thicknesses of flexible armor material, including but not limited to aramids (e.g. Kevlar® fabric or other suitable material). Layer 2B is preferably formed from a flexible polymer foam or other suitable material. Layer 2A, is preferably formed from aluminum or other suitable material. Layers 2A, 2B and 2C, working together, absorb the residual blast energy and provide protection against stray fragments. Layers 2A, 2B and 2C also provide a reduced measure of second hit protection, should another round strike the tile 10 after it has functioned, but before it can be replaced.

Table 1 lists preferred materials, sizes, weights, and thicknesses for each layer of system 16, for a given threat, although other materials, sizes, weights and thicknesses may be utilized, depending on the particular applications. TABLE 1 Electrically Initiated Very Lightweight Reactive Appliqué Armor Components Representative Weight (lb) Thickness Square 2″ × 2″ 3″ × 3″ 4″ × 4″ Layer Material (in) Foot Tile Tile Tile 2A Thin ductile metal 0.0359 to 0.06 0.5 0.01 0.03 0.06 2B Flexible polymer foam, ˜1 pcf 0.5 to 1.25 0.5 0.01 0.03 0.06 2C High strength polymer fabric 0.15 to .4 0.8125 0.02 0.05 0.09 armor material (e.g., DuPont's Kevlar ®) 2D RPF, 6 pcf 2.0 to 5.0 1.25 0.03 0.08 0.14 4E Sheet explosive, such as 0.08 to 0.16 0.95 0.03 0.06 0.11 DuPont C-2, C-3, or C-4 Detasheet ® 6F Rigid polymer foam ˜1 pcf 0.25 to 0.75 0.03 0.00 0.00 0.00 8G Thin ductile metal 0.0359 to 0.06 0.50 0.01 0.03 0.06 8H Polymer 0.05 to 0.2 7.3E−05 0.00 0.00 0.00 8J Thin ductile metal 0.0359 to 0.06 0.50 0.01 0.03 0.06 System Very lightweight reactive 3.14 to 7.94 5.06 0.14 0.32 0.56 16 appliqué armor Composite Tile =

System 16 includes firing set 18 connected by wires 20 to layers 8G and 8J and to a power source 22, such as a twelve volt battery or the like. Firing set 18 is also connected by wires 24 to detonator 26, which is embedded within explosive layer 4E. When incoming projectile 14 completes an electrical circuit between layers 8G and 8J, firing set 18 sends a signal to detonator 26 to explode, which causes entire explosive layer 4E to explode, defeating projectile 14. The force of the explosion of explosive layer 4E is contained by layers 2A, 2B, 2C, and 2D, as outlined in more detail above.

The materials and thicknesses shown in Table 1 may be modified based on specific requirements, as will be appreciated by those skilled in the art. Firing set 18 is not detailed and components for mechanical and electrical mounting of tile 10 to surface 12 and firing set 18 to vehicle are not shown but preferably utilize suitable mechanical and electrical mounts and/or fasteners as will be appreciated by those skilled in the art.

In percussion initiated (non-electric or NONEL) reaction embodiments of very lightweight reactive appliqué armor system, indicated generally at 30, each tile 10 preferably has a cross-section such as that shown in FIG. 4. The NONEL reaction system 30 differs from the system 16 by a variation in the trigger layer 8 and by the omission of spacer layer 6, outlined in more detail above. Energy absorbing layer 2 still has three sub-layers, though it may have more. In system 30, the sub-layers of trigger layer 8 are designated 8X, 8Y, and 8Z. System 30 includes energy absorbing layer 2 having four sub-layers, designated 2A, 2B, 2C, and 2D, similar to system 16.

In system 30, layer 8Y may be a primary explosive, or it may be an explosive of lesser sensitivity, similar to PETN, which has been determined to be able, through the proper shaping of layers 8× and 8Z, to be initiated by a projectile impact. Layer 8X serves as the “anvil” and layer 8Z, the “hammer” of the percussive trigger, as will be appreciated by those skilled in the art. The surfaces of layers 8X and 8Z that are in contact with layer 8Y preferably have complementary contours shaped for efficient compression of layer 8Y. Layer 8X has vent holes 32 to permit the blast wave generated by detonation of layer 8Y to efficiently pass through onto the surface of explosive layer 4E, the “bulk charge”. The combination of layers 8X, 8Y and 8Z, comprising the trigger layer 8 are preferably configured such that percussive blows with less than a threshold energy, or less than a threshold power will not cause initiation and subsequent explosion of explosive layer 4E, while percussive blows that exceed the threshold in both energy and power do cause initiation and subsequent explosion of explosive layer 4E.

The preferred embodiment of the present invention relates to a very lightweight reactive appliqué armor system 1, 16, or 30. The armor system 1, 16, or 30 is similar in function to the reactive appliqué armor known in the art, but has several significant differences. The system 1, 16, or 30 of the present invention preferably provides a very lightweight reactive appliqué armor containing an energy absorbing layer between the surface of the vehicle and the explosive layer, permitting its use on unarmored vehicles. In addition, the very lightweight reactive appliqué armor comprises a number of different layers, each with a specific function, permitting tailoring performance of the armor of the present invention to match a threat or given spectrum of threats. Additionally, the system 1, 16, and 30 is preferably fabricated from commercial-off-the-shelf components, none of which requires difficult or expensive manufacturing processes, and may advantageously be formed in flat sheets, complex curved panels, or field replaceable tiles. The system 1, 16, and 30 is intrinsically light in weight; and can be quickly installed or removed without requiring the use of special equipment.

Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. 

1. A multi-layer lightweight protective armor system for application to an unarmored vehicle, comprising: an energy absorbing layer adapted to be mounted adjacent an exterior vehicle surface; an explosive layer formed from an explosive material and disposed on said energy absorbing layer; and a trigger layer disposed on said explosive second layer, said trigger layer operable to initiate an explosion in said explosive layer when a projectile impacts said trigger layer, said energy absorbing layer operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.
 2. The system of claim 1 wherein said energy absorbing layer includes a plurality of sub-layers.
 3. The system of claim 2 wherein said energy absorbing sub-layers are formed from at least one material selected from the group consisting of RPF, metal, polymer, flexible polymer foam, and high strength polymer fabric material.
 4. The system of claim 1 wherein said layers of said system are formed in the shape of a tile and said system comprises a plurality of said tiles arranged in an array on the exterior vehicle surface.
 5. The system of claim 1 where each of said tiles has an aspect ratio of approximately 1.0.
 6. The system of claim 1 wherein said explosive layer is formed from an explosive material.
 7. The system of claim 6 wherein said explosive material comprises at least one material selected form the group consisting of PETN, C-2, C-3, and C-4.
 8. The system of claim 1 wherein said trigger layer includes a plurality of sub-layers.
 9. The system of claim 1 wherein said trigger sub-layers are formed from at least one of material selected from the group consisting of a metal and a polymer.
 10. The system of claim 1 wherein said trigger layer initiates an explosion utilizing a percussion plate.
 11. The system of claim 1 wherein said trigger layer initiates an explosion utilizing an electrical initiation system.
 12. The system of claim 11 further comprising a detonating device disposed in said explosive layer.
 13. The system of claim 12 further comprising a spacer layer disposed between said explosive layer and said trigger layer.
 14. A multi-layer lightweight protective armor system for application to an unarmored vehicle, comprising: an energy absorbing layer adjacent an exterior vehicle surface; an explosive layer disposed on said energy absorbing layer, said explosive layer including a detonator disposed therein; a spacer layer disposed on said explosive layer; a trigger layer disposed on said spacer layer; and a firing set including a detonator disposed in said explosive layer, said trigger layer operable to send a signal to said firing set when a projectile impacts said trigger layer, said firing set operable to detonate said detonator to initiate an explosion in said explosive layer, and said energy absorbing layer operable to contain said explosion and prevent the explosion from reaching the exterior vehicle surface.
 15. The system of claim 14 wherein said energy absorbing layer includes a plurality of sub-layers.
 16. The system of claim 15 wherein said energy absorbing sub-layers are formed from at least one material selected from the group consisting of RPF, metal, polymer, flexible polymer foam, and high strength polymer fabric material.
 17. The system of claim 14 wherein said trigger layer includes a plurality of sub-layers.
 18. The system of claim 17 wherein said trigger sub-layers are formed from at least one material selected from the group consisting of a metal and a polymer.
 19. The system of claim 18 wherein said trigger layer sends a signal to said firing set when the projectile completes an electrical circuit between two of said trigger sub-layers.
 20. A multi-layer lightweight protective armor system for application to an unarmored vehicle, comprising: an energy absorbing layer adjacent an exterior vehicle surface; an explosive layer disposed on said energy absorbing layer, said explosive layer including a detonator disposed therein; and a trigger layer disposed on said second layer, said trigger layer including a percussion plate operable to initiate an explosion in said explosive layer when a projectile impacts said trigger layer, said energy absorbing layer operable to contain the explosion and prevent the explosion from reaching the exterior vehicle surface.
 21. The system of claim 20 wherein said energy absorbing layer includes a plurality of sub-layers.
 22. The system of claim 21 wherein said energy absorbing sub-layers comprise at least one material selected from the group consisting of RPF, metal, polymer, flexible polymer foam, and high strength polymer fabric material.
 23. The system of claim 20 wherein said trigger layer includes a plurality of sub-layers.
 24. The system of claim 23 wherein said trigger sub-layers are formed from at least one material selected from the group consisting of a metal and a polymer.
 25. The system of claim 24 wherein at least one of said trigger sub-layers is a percussion plate, another of said trigger sub-layers is an anvil layer, and another of said trigger sub-layers is a hammer layer.
 26. The system of claim 25 wherein the surfaces of said anvil layer and said hammer layer in contact with said percussion plate include complementary contours shaped for efficient compression of said percussion plate. 